| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | EVP_OpenInit, EVP_OpenUpdate, EVP_OpenFinal - EVP envelope decryption
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| 6 |
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| 7 | =head1 SYNOPSIS
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| 8 |
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| 9 | #include <openssl/evp.h>
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| 10 |
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| 11 | int EVP_OpenInit(EVP_CIPHER_CTX *ctx, EVP_CIPHER *type, unsigned char *ek,
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| 12 | int ekl, unsigned char *iv, EVP_PKEY *priv);
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| 13 | int EVP_OpenUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
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| 14 | int *outl, unsigned char *in, int inl);
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| 15 | int EVP_OpenFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
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| 16 |
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| 17 | =head1 DESCRIPTION
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| 18 |
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| 19 | The EVP envelope routines are a high-level interface to envelope
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| 20 | decryption. They decrypt a public key encrypted symmetric key and
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| 21 | then decrypt data using it.
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| 22 |
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| 23 | EVP_OpenInit() initializes a cipher context B<ctx> for decryption
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| 24 | with cipher B<type>. It decrypts the encrypted symmetric key of length
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| 25 | B<ekl> bytes passed in the B<ek> parameter using the private key B<priv>.
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| 26 | The IV is supplied in the B<iv> parameter.
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| 27 |
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| 28 | EVP_OpenUpdate() and EVP_OpenFinal() have exactly the same properties
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| 29 | as the EVP_DecryptUpdate() and EVP_DecryptFinal() routines, as
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| 30 | documented on the L<EVP_EncryptInit(3)> manual
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| 31 | page.
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| 32 |
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| 33 | =head1 NOTES
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| 34 |
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| 35 | It is possible to call EVP_OpenInit() twice in the same way as
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| 36 | EVP_DecryptInit(). The first call should have B<priv> set to NULL
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| 37 | and (after setting any cipher parameters) it should be called again
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| 38 | with B<type> set to NULL.
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| 39 |
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| 40 | If the cipher passed in the B<type> parameter is a variable length
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| 41 | cipher then the key length will be set to the value of the recovered
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| 42 | key length. If the cipher is a fixed length cipher then the recovered
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| 43 | key length must match the fixed cipher length.
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| 44 |
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| 45 | =head1 RETURN VALUES
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| 46 |
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| 47 | EVP_OpenInit() returns 0 on error or a non zero integer (actually the
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| 48 | recovered secret key size) if successful.
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| 49 |
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| 50 | EVP_OpenUpdate() returns 1 for success or 0 for failure.
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| 51 |
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| 52 | EVP_OpenFinal() returns 0 if the decrypt failed or 1 for success.
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| 53 |
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| 54 | =head1 SEE ALSO
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| 55 |
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| 56 | L<evp(7)>, L<RAND_bytes(3)>,
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| 57 | L<EVP_EncryptInit(3)>,
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| 58 | L<EVP_SealInit(3)>
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| 59 |
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| 60 | =head1 COPYRIGHT
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| 61 |
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| 62 | Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
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| 63 |
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| 64 | Licensed under the Apache License 2.0 (the "License"). You may not use
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| 65 | this file except in compliance with the License. You can obtain a copy
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| 66 | in the file LICENSE in the source distribution or at
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| 67 | L<https://www.openssl.org/source/license.html>.
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| 68 |
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| 69 | =cut
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